The main area code, 601, was one of the original area codes implemented in 1947, and covered the entire state of Mississippi. Despite the state's relatively stagnant population growth, 601 was close to exhaustion by the mid-1990s due to the proliferation of cell phones. Additionally, the MemphisLATA extends for some distance into northern Mississippi, so several numbers in Memphis' area code 901 weren't available for use. In 1997, the far southeastern portion tip of the state, including Biloxi and the Gulf Coast, was split off as area code 228. In 1999, area code 662 was created in the northern half of Mississippi, including the Mississippi side of the Memphis area.

The 1999 split was intended as a long-term solution, but within five years 601 was close to exhaustion due to the proliferation of cell phones, particularly in the Jackson area. In 2005, Mississippi's first overlay area code, 769, was approved for use to overlay 601. Ten-digit dialing became mandatory in central Mississippi later that year.